Problem 1. On page 32 of the notes set "3_microfab_trad2_spr16.pdf" there is a list of other processes for inorganic materials; in class we only covered the ones with stars * next to them (e.g., ultrasonic micromachining, etc.) in class. Please pick one of the others without a star, find an article discussing the method for an application in biomedical microdevices and systems, and do the following:
Describe: i) the process; ii) the application in biomedical microdevices and systems or microfluidics presented in the article; iii) another application that could potentially benefit from the fabrication process, with reasoning that supports why you chose this (new) application. Be sure to:
a) List the article at the bottom of the page using any conventional bibliography format, provided it lists ALL authors, the complete title of both the article and where it was published, and indexing info so that I can find it easily.
b) Keep your answer to one page maximum, one side, 12 point font and 1 inch margins on all side. All text and supporting figures must fit into the one page, including the reference.
Problem 2. We wish to fabricate the structures below in silicon for attaching together two microfluidic substrates. Outline a fabrication process flow to fabricate these structures using standard 0.5-mm-thick silicon wafers (as many as you need) so that they will slide together as shown with the approximate size specifications given (for those not given, just make sure that you will get the structures as shown). Please note that these figures are not necessarily drawn to scale.
Problem 3. Similarly to the structures in Problem 2, tee-shaped rails may be used to interlock two components together while still allowing them to slide against each other in one direction (along the rails). Outline a fabrication process flow to fabricate the following SU-8 "tee-rails" on glass substrates where the tops of the rails overhang empty space like cantilevers.
Problem 4. You wish to make the following structure (cross-section) out of silicon. Suggest a process flow for fabrication of the structure. (Hint: both silicon dioxide and photoresist can be used as DRIE masks)
Problem 5. You are designing a mechanically flexible glucose sensor to be placed in a contact lens in the eye to measure glucose levels in tears. We will discuss glucose sensor operation later in the course. For now, however, we want to design a fabrication process for a prototype that we will use to test the sensor operation in vitro. For the prototype sensor, we need three metal electrodes, each with a 1 mm2 open area, that are connected via metal lines 100 µm wide to metal bond pads 0.5 mm2 on the other (lengthwise) side of the chip. The chip is to be 5 mm wide and 8 mm long. We will be dipping the electrodes in solution. The metal lines must be insulated against solution, but the electrodes should be open to solution and the bond pads also not covered so that we can attach wires for testing. The entire sensor needs to be mechanically flexible so that it can bend for molding in a contact lens
a) Draw a figure of the proposed sensor, indicating all sizing information (even that not given in the problem description). Be sure to specify substrate thickness, metal thickness, etc.. You may have to consider parts b and c also when drawing your figure.
b) What materials do you propose to use for the metal, insulation over the metal lines, and substrate? Justify your answers.
c) Outline a process flow to realize the sensor structures shown in (a) using the materials in (b).
Problem 6. Give examples of when injection molding may be a preferred fabrication technique compared to hot embossing, and vice versa (hot embossing preferable to injection molding). You may state device characteristics or specific devices. Please confine your entire answer to no more than half a page of typewritten text or the equivalent.